under the shore excursions list I found the "private island snorkeling tour " for 29 $.
Is this for the snorkeling equipment only?
What if I bring my own equipment? Is this the charge for entering great stirrup cay ? Or can I just go offboard and spend the day on my own?
I hope somebody can help?

hey! great stirrup cay is one little private island for the norwegian ship. BRING your own snorkel! or else you will have to pay for the equipment. and they do not take you to a special area. the tenders bring you ashore and you all swim in the same place - whether you paied for the excursion or not oh, and bring goldfish or crackers... they bring the fish up! trust me, you do not need to pay for that excursion! and the snorkels look dirty. hope that helped! (basically you would snorkel right next to the people who bought their own equipment... you get nothing special!)